Harry Potter and the Mystic Arcanum
by Darth-Vulturnus
Summary: Voldemort had been defeated and people were reveling in his defeat across Magical Britain. Unfortunately for the boy-who-lived-to-vanish, his new residency in Faerun meant his troubles were only beginning. On the bright side, he wouldn't be alone and at least he'd have rightfully earned his fame. D&D crossover, HP AU.


**Prologue**

* * *

 **Godric's Hollow, 1981**

Lord Voldemort was a man few wished to cross. His reputation alone scared away all but the most skilled and most foolish. But tonight, he would finally have a chance to deal with some of those thanks to the treachery of Peter Pettigrew.

A weak traitor looking for a better lot in life indeed and how foolish of those in Dumbledore's group to not see it. But then, what could be expected from Gryffindors?

No matter.

After he finished this business with the Potters, thus dealing with that minor prophecy young Severus had brought to him before the boy grew up and became dangerous, he would reward Pettigrew as much as he deserved.

The gate to the Godric's Hollow abode creaked open as he walked up the small path, pushing open the door. Only to find James Potter, rapidly jumping up from his position on the couch.

"Lily!" He called futility, "It's him! He's here! Take Harry and run! I'll hold him off!"

Voldemort almost smirked...almost, "You will, will you James Potter? Without your wand? How utterly foolish."

With two flicks of his yew wand, the male Potter was lying unconscious on the floor, stiff as board. If Potter had possessed his wand, and thus actually been a minor hassle to deal with, he probably would have just killed him to save the trouble. But the young man had been defenseless. Very brave, but ultimately defenseless.

Despite the personal weakness of the current Potter, the line was still good, no need to snuff out another line. Besides, Voldemort was only surpassed by Dumbledore in the mind arts. So long as he kept Potter away from that fool, keeping him reeducated and working for him could be very useful.

Oh, he could imagine the headlines now.

 _James Potter's Dirty Secret Revealed! Actually a Death Eater!_

Stepping over the prone body of his new toy, he casually made his way up the stairs, taking an extra moment looking for a potential ambush or trap. Regardless what he thought of her blood, he did have to admit that Lily Potter was crafty, especially given set up time. He could certainly understand why a lesser man like James Potter had fallen for her.

But it seemed he would not have to go far, as she was defensively standing in front of a room.

"Lily Potter. Stand aside."

She glared at him, green eyes narrowed in as much hate at him as concern for her child in the room behind her, "Voldemort. If you think I'd do that, you must not know me very well."

Giving her a disappointed look, he said, "Severus wasted good time grovelling for me to spare your life. I would hate to have to tell him that his hopes were in vain."

"I won't just let you kill my child and husband while letting me live. Severus lost all right to have anything to do with me years ago. While I live, you will not touch my child."

Why are mothers always so difficult, he mentally groaned. This one especially. Severus was the best potion brewer of the Death Eaters, and Voldemort knew well the depths of the man's unhealthy obsession with his childhood friend. It would be a real shame to lose his skills.

But Lord Voldemort wasn't a master of the mind arts for nothing. And with his particular skills came a rather potent ability to multi-task.

"Imperio."

As the spell settled on her, he could tell she was already fighting it and would break free momentarily. But unlike previous times, there was nowhere for her to escape to. And he only needed a moment in quarters this close.

The ruby light of a stunner lashed out from his wand, making impact within milliseconds. He waited a moment as her unconscious body collapsed in a undignified heap on the floor. Giving her the same treatment as her husband and watching as her limbs snapped tight to her body via the full body bind, he finally reached his destination.

"And so we meet at last, Harry Potter, the boy apparently prophesied to defeat me."

The baby in the crib just stared at him.

Taking a moment to recognize his audience, he placed his palm over his face, "And now I'm monologuing to a baby. I need to spend less time with Bellatrix. Let's get this over with."

Pointing his wand at the child, he only said, "Avada Kedavra."

No one would ever quite be sure what happened next. To say the spell rebounded would be an easy, albeit, wrong answer. All that was known was that when the ominous green light died down, there were two piles of clothes. One those of an infant and the other those of an adult wizard.

For better or worse, both Harry Potter and Tom Riddle were gone, the latter reduced to less than a ghost and the former translocated to another plane entirely.

* * *

A piece of siding flew through the space Albus Dumbledore had been a moment ago as he casually sidestepped the fifth one in the past few minutes.

Extinguishing another potential fire hazard before it became an issue, he said gently, "Rubeus, I understand you're worried for them. I am as well. But if we hurt ourselves, what can we do for them?"

Hagrid paused for a moment, likely contemplating the point, before reaching down more carefully and placing them more carefully to the side, saying "Yer right perfessor, you always are. Why didn't young Sirius Black stay?"

Albus Dumbledore, sighed, feeling all of his century of age, saying, "He has gone to track down Peter Pettigrew, the secret keeper and man who sold Lily and James to Voldemort. I tried to convince him otherwise, but he would not be deterred."

As Hagrid shuffled through the debris, he reached down and the next thing he personally brought over. It was not, as Albus has first assumed, a Potter heirloom to be kept as a memento, but the body of James Potter himself. Such a shame that a bright young man had been taken from them so soon, but that was a risk of fighting against Voldemort, unfortunately.

"He's still alive."

Of all the things Hagrid could have said, that one probably surprised him the most.

"Is he?"

Looking closer Dumbledore could recognize the shallow rise and fall of breathing. A full-body bind and a stunner instead of the killing curse...what was Tom up to?

"Lay him down and go see if you can find Lily and Harry, Rubeus. I can handle James for the moment."

While Hagrid trudged back into the fray, Albus took a few steps back as he began casting. While he was confident he could undo any damage done to someone still living, it was better to be cautious.

With even less effort than Voldemort had put in, James Potter was freed from his bonds, and immediately rolled over and hurled the contents of his dinner over the asphalt.

"Welcome back to the land of the conscious, James."

Slowly pushing himself back onto his feet, he stood up taking in the scene, "Dumbledore? What happened?"

Giving the much younger man a hand to help steady himself, Albus frowned, saying, "I was about to ask you the same thing, actually. Sirius has filled me in on the secret keeper switch, while I am loath to say that I told you so, I feel I must. I would have been more than happy to have served as secret keeper for you three."

"Ugh, can we not focus on that part right now? Wait...where's Lily and Harry?"

Before James could run into the cottage that was quickly losing its structural integrity, he unwillingly froze.

He snarled, attempting to move, but had no such luck, "Let me go Dumbledore, I need to go and help."

"As you are, you would only put yourself in danger. Rubeus shall return shortly," Albus stated, as he returned to his mitigation of physical dangers to make it as safe for Hagrid as possible.

True to Albus' word, Hagrid waded out through the wreckage just a couple minutes later, Lily's distinctive red hair visible under one of his massive arms. Letting James free, the two walked up to Hagrid as he set Lily down on the pavement, as well as dropping a bundle of things on the ground. When he got to the last item, he stopped and examined it for a moment before handing it off to Albus.

"Rubeus, where did you find this?"

James leaned over, looking at the wand now in Dumbledore's hand, asking, "Is that...Voldemort's wand?"

Nodding, Dumbledore responded gravely, "It is indeed. A foul perversion of Ollivander's work, unmistakeable. What this means I can only make guesses, but all the evidence does point to Tom having lost tonight. He would never abandon his wand willingly. It is perhaps one of his most valuable possessions. I recognize his robes as well. Unfortunately, I do not believe him to be dead."

"What? Why?" James exclaimed.

"A man as foul as Voldemort will have used or created ways to stay alive no matter the cost. It may take him years, but having a physical body destroyed, as it seems based on our evidence here, will only slow him down."

Reaching down and reviving Lily, she shot up, frantically looking around, speaking a mile a minute, "What's going on? Where's Voldemort? Why am I outside? Where's Harry?"

Half stumbling over, James placed his hands on her shoulders, "Calm down Lils. But that's a good question. Hagrid, where is Harry?"

After rubbing off some of the soot on his jacket, Hagrid wiped his eyes, "I couldn't find 'im anywhere."

"You found nothing, Rubeus? No signs at all?"

"No, perfessor. Just his clothes in the crib. Ah, I shoulda looked 'arder!"

Albus placed a consoling hand on the man's shoulder, "I trust that you did the best you possibly could. As it is, nearly anything could have happened to young Harry. For the time being -"

He was cut off angrily by James, "And we're just to forget that our son is _gone_? Just move on with our lives?"

"No James, I am not suggesting that. What I am proposing is that attempting to discover Harry's fate will undoubtedly take time. While I ask for your help in this project, you should not let it consume you. I have never attempted something like this before, I know not how it shall go."

* * *

 **Ministry of Magic, 1981**

"Bring in the defendant."

An unearthly chill seeped into the room as two dementors entered the room, each holding a thick chain. Being restrained by the chains was a young man, barely out of his Hogwarts years, his shaggy black hair falling to his shoulders.

Once the man had been suspended in the chair, he gave a small grimace towards the audience.

From the high rose seat looking down upon the accused, the voice spoke again, "November 8th, 1981. Ministry of Magic against Sirius Black. Mr. Black is accused of the murder of Peter Pettigrew, thirteen muggles and Class 1 Breach of the Statue of Secrecy. How does the accused plead?"

Sirius Black turned slightly, glancing over those gathered. For a moment, his eyes stopped over a set people before he turned back to the head of the DMLE.

His lips pulled back, canines prominent as he declared, "Guilty."

A gavel hit the wood in the otherwise silent courtroom.

"As per the guilty plea deal between the prosecution and the defense, Sirius Black is to be executed by the Department of Mysteries."

Two aurors walked up, loosening him from the chair before placing a set of steel handcuffs on Sirius as they proceeded to walk him out of the courtroom towards his executioners.

And if they noticed how their young charge held his head high and pointedly looked away from the distraught Potters and a disappointed Dumbledore, they said nothing at all.

* * *

 **Far Realms, 1368 DR**

After walking through the Veil of his own accord, Sirius was expecting the cold embrace of death and perhaps an eternity of oblivion. At best he hoped his valiant actions against Voldemort and his minions would be noticed and he could spend an eternity surrounded by his favorite things, to eventually be joined by his friends and what small parts of his family he liked.

But this? He had never, in all his wildest dreams expected something like this.

"What is this? Just where am I?"

Reality had seemingly stepped outside for a smoke break as he looked around, tentacled monstrosities that hurt just to look at floated by him, stars of unnatural colors danced in the sky, all seemingly oblivious to both his presence and that of physics.

"Maybe Azkaban wouldn't have been so bad after all… ," he muttered darkly under his breath, "It'd certainly have been less...strange."

Unconsciously reaching for his wand before he remembered they had taken it from him, he was equally surprised to find it back in his pocket where he had previously left it.

As he raised it however, it was if a beacon was lit. The eldritch beings turned nearly as one to look at him, and Sirius swore he could see what might pass for saliva and dark, forked tongues.

Nowhere to run.

Nowhere to hide.

His wand lit with the glow of some of the most powerful battle magic known to humankind, he braced himself for the inevitable onslaught as he yelled defiantly, "If you want me for dinner so badly, come and get me!"

* * *

 **Malbolge, 1408 DR**

Towers jutted out amongst fortress, once resplendent. Now however, the bone white stones stood out vividly against the landscape. Greasy trees, twisted flowers and reflecting pools of clear poisons swept the once beautiful realm. The sixth level of Hell, Malbolge, was both the most beautiful and ugliest of the levels. As much as its architecture was disparate from the other eight layers, its presence became a dark twisted reminder of what once was.

Long ago, with the creation and coming of the devils.

Upon a throne of bone and adamantium sat the most recent ruler of the realm, her copper skin reflecting the red light as leathery wings folded themselves tightly against her back.

"M'lady! Lady Glasya!"

Looking down from the raised platform her throne sat upon, the corpulent form of the amnizu serving as her vizier per orders from her father, she turned her attention from her schemes to more immediate concerns.

"What is so important that requires my attention?"

"Somehow, a human child has managed to infiltrate our defenses! Surely this is the work of the Abyss!"

Giving a long-suffering sigh, and desperately wishing she could dismiss the useless amnizu without incurring another lecture from her father, she simply stood up and followed the annoyance. And when she got there she was less than impressed.

"A human infant, Jager, you brought me here for a human _infant_?"

Reaching down and scooping the child out of the small crater into her arms, she paused for a moment, running a finger over the angry red scar, "Oh? Whatever do we have here?"

A shard of a soul resided within the scar, a soul fragment that did not belong to the child, but instead another. How interesting. Calling upon her not insignificant powers, she reached through the child's physical body towards his soul before grabbing hold of the fragment that was slowly attempting to embed itself and forcibly removed it.

The black tar-like substance rested fluidly in her hands for a moment before it was destroyed as she crushed it. Glasya took a moment to breathe in as the memories of the shard flooded into her. A mortal might have been unconscious for days as it was assimilated, the shard even potentially wresting control should its opponent be weak willed.

But Glasya was not mortal. She was the daughter of Asmodeus, ruler of Hell. An archdevil in her own right, and the sixth layer of Hell was her domain. No mortal stood a chance against her in her own home, not even a megalomaniac like this 'Lord Voldemort' seemed to be, especially with his utter failure at immortality. Lichdom wasn't achieved by splitting your soul after all.

"M'lady, what are we do with the child? Shall we dispose of it for you?"

She looked down at the dark haired child in her arms who seemed to be sleeping more restfully than before, doing his best to snuggle against her warmth, smiling lightly, "No, no. I have plans for this one."

After all, he was the only connection to this new world she had. He might be the key she needed. Well aware of how fragile human infants were, she slowly began to infuse Harry with bits of her power, carving her personal mark of power into his very soul. It wasn't much now, but enough that its intoxicating nature of her magic would make sure he'd come to her for more in the future before looking for magic elsewhere.

"If you say so, M'lady, though I confess to not quite seeing the point."

"This is why you have not yet been promoted to pit fiend, Jager. Always in such a rush. We can afford to play the long game. Some trees take decades to bear fruit."

It didn't really matter in the end whether Harry Potter would help her in the way she wanted. There was no harm in trying. Another powerful mortal, as young Harry here was destined to be, under her banner would be helpful regardless of the nature.

With a flick of her wrist and light jangling of jewel encrusted bracelets, the child was plane-shifted to a suitable location, one where she felt the pull of another, but for the life of her could not identify. That she could still feel him was a good sign, and utterly necessary for the future as she sang lullabies she had learned over the centuries telepathically into the distraught child's mind. Plane shifting did always tend to be a bit disorienting for mortals, and her new pet project would need a softer hand.

There was no rush. She would find a way to utilize all the knowledge Tom Riddle had unwillingly given her eventually. After all, she herself had forever and Harry Potter's soul already belonged to her. There was no rush. None at all.

* * *

 **Shadowdale, 1408 DR**

Matron Nerre could under no circumstances be called young. Her stern demeanour and stark white hair saw to that. But one thing no one with any brains would accuse her of would being undedicated to her job.

She had, after all, worked in some capacity at Shadowdale's orphanage for nearly six decades.

As she walked back up the steps, her eyes caught on two infants, one possessed of dark hair and the other of blond, resting peacefully on the stone steps, "Oh, for the sake of Lathander. Must people just leave them here with nothing?"

Reaching down and gently scooping up the two, she brought them into a washroom and began to clean them, starting with the crusted, dry blood on the forehead of the dark haired child.

With the blood removed, she took a closer look, "Oh you poor child. What's been done to you?"

Angry red lines traced down his forehead, in a vague imitation of how a child might draw a thunderbolt. But the lines were straight and aside from being seemingly fresh, were fairly clean. Luckily, the blond one seemed to have escaped whatever befell his companion.

Nerre gave the long suffering sigh of general disappointment with humanity and lack of hope for future generations that only the elderly can truly pull off, "Accidents don't cause wounds like this. Why would someone carve this into you and then drop you here? It doesn't make any sense."

She got no response, nor was she expecting one. A powerful cleric of Lathander she may be, but since the SpellPlague, communique from her god could be counted on one hand. Not that she blamed him, truly.

Wrapping the children up, she brought them over to the nursery where other children of similar age were congregated. Placing them in one of the spare cribs, she took a moment to look over the sleeping infants before heading off to her own room.

Light poured through the uncovered window, the harsh light of distant stars glaring down. But tonight she felt as if some were judging her personally. How her husband slept so peacefully under it, she would never understand.

Fifty years ago in the middle of the Time of Troubles as it was called, strange things had been afoot. She was no scholar herself, but when those who are offering warnings, it is often best to heed their advice. An adventurer in her youth, her group would have died many a time if they had not taken the often unfortunate truths their sorcerer and rogue had told them, usually regarding dungeon traps.

For near a minute the intense light shone on her, before seemingly making their judgement for good or bad and turning away.

Closing the curtains with some trepidation, she made her way into bed next to her husband of forty years. While they could never have children of their own, courtesy of illness in her youth and the eddy of wild magic that had given him his arcane powers, running the orphanage had helped fill a void in both their hearts left by numerous events, both before and after they met.

Nerre hadn't lived this long by not being cautious. But her knowledge of some of the more esoteric matters were questions for others. Her husband had never professed to be scholarly, and while questions of the divine she knew by heart, questions of the arcane not so much.

A wizened hand placed itself on her shoulder, and she turned over to face her husband, a concerned look upon his face, "Everything alright love?"

She gave a light sigh, "I'll tell you in the morning."

Well used to her habit by now, he asked, "Are you sure?"

At her nod, he continued, "Alright….good night, Nerre."

"Good night, Sirius."

* * *

 **Notes:** An idea that got stuck in my head. Not sure how long it'll be, since I have a terrible habit of not finishing things. As this is a habit I'm striving to break, this probably won't be terribly long to make sure I can keep interest and ideas, and will probably be in the format a few massive chapters with no ordained update schedule as opposed to many small ones. For those of here from Partners, no, it's not dead. That's still my main project. This is just an amusing side-gig, so don't expect anything super deep in terms of philosophy, backstabbing and incredibly complex plot. As for why I didn't put this in the proper crossover category...I shamelessly know it'll get more hits this way, which I admit, does help my motivation.


End file.
